/* * __get_user functions. * * (C) Copyright 1998 Linus Torvalds * (C) Copyright 2005 Andi Kleen * (C) Copyright 2008 Glauber Costa * * These functions have a non-standard call interface * to make them more efficient, especially as they * return an error value in addition to the "real" * return value. */ /* * __get_user_X * * Inputs: %[r|e]ax contains the address. * The register is modified, but all changes are undone * before returning because the C code doesn't know about it. * * Outputs: %[r|e]ax is error code (0 or -EFAULT) * %[r|e]dx contains zero-extended value * * * These functions should not modify any other registers, * as they get called from within inline assembly. */ #include <linux/linkage.h> #include <asm/dwarf2.h> #include <asm/page.h> #include <asm/errno.h> #include <asm/asm-offsets.h> #include <asm/thread_info.h> #include <asm/asm.h> .text ENTRY(__get_user_1) CFI_STARTPROC GET_THREAD_INFO(%_ASM_DX) cmp TI_addr_limit(%_ASM_DX),%_ASM_AX jae bad_get_user 1: movzb (%_ASM_AX),%edx xor %eax,%eax ret CFI_ENDPROC ENDPROC(__get_user_1) ENTRY(__get_user_2) CFI_STARTPROC add $1,%_ASM_AX jc bad_get_user GET_THREAD_INFO(%_ASM_DX) cmp TI_addr_limit(%_ASM_DX),%_ASM_AX jae bad_get_user 2: movzwl -1(%_ASM_AX),%edx xor %eax,%eax ret CFI_ENDPROC ENDPROC(__get_user_2) ENTRY(__get_user_4) CFI_STARTPROC add $3,%_ASM_AX jc bad_get_user GET_THREAD_INFO(%_ASM_DX) cmp TI_addr_limit(%_ASM_DX),%_ASM_AX jae bad_get_user 3: mov -3(%_ASM_AX),%edx xor %eax,%eax ret CFI_ENDPROC ENDPROC(__get_user_4) #ifdef CONFIG_X86_64 ENTRY(__get_user_8) CFI_STARTPROC add $7,%_ASM_AX jc bad_get_user GET_THREAD_INFO(%_ASM_DX) cmp TI_addr_limit(%_ASM_DX),%_ASM_AX jae bad_get_user 4: movq -7(%_ASM_AX),%_ASM_DX xor %eax,%eax ret CFI_ENDPROC ENDPROC(__get_user_8) #endif bad_get_user: CFI_STARTPROC xor %edx,%edx mov $(-EFAULT),%_ASM_AX ret CFI_ENDPROC END(bad_get_user) .section __ex_table,"a" _ASM_PTR 1b,bad_get_user _ASM_PTR 2b,bad_get_user _ASM_PTR 3b,bad_get_user #ifdef CONFIG_X86_64 _ASM_PTR 4b,bad_get_user #endif